Aquarium Systems Test Kit A new range of test kits from Aquarium Systems that accurately test your marine and freshwater aquarium water. Ensuring nitrate (NO3) levels in your aquarium remain within normal limits is essential for fish health, and to prevent excessive algae growth. This Aquarium Systems Seatest Nitrate test kit provides around 40 individual tests, indicating when water changes should be performed. Please note this product is short dated - BBE August 2015.